Intraluminal, intracavity, intravascular, and intracardiac treatments and diagnosis of medical conditions utilizing minimally invasive procedures are effective tools in many areas of medical practice. These procedures are typically performed using imaging and treatment catheters that are inserted percutaneously into the body and into an accessible vessel of the vascular system at a site remote from the vessel or organ to be diagnosed and/or treated, such as the femoral artery. The catheter is then advanced through the vessels of the vascular system to the region of the body to be treated. The catheter may be equipped with an imaging device, typically an ultrasound imaging device, which is used to locate and diagnose a diseased portion of the body, such as a stenosed region of an artery. For example, U.S. Pat. No. 5,368,035, issued to Hamm et al., the disclosure of which is incorporated herein by reference, describes a catheter having an intravascular ultrasound imaging transducer. These are generally known in the art as Intravascular Ultrasound (“IVUS”) devices.
FIG. 1 shows an example of an imaging transducer assembly 1 known in the art. The imaging transducer 1 is typically within the lumen 10 of a guidewire or catheter (partially shown), having an outer tubular wall member 5. To obtain an image of a blood vessel the imaging transducer assembly 1 may be inserted into the vessel. The transducer assembly 1 may then interrogate the cross-sectional plain of the vessel from the inside by rotating while simultaneously emitting energy pulses, e.g., ultrasound pulses, and receiving echo signals.
It may be desirable to obtain not only a cross-sectional plane of the vessel, but also information on blood flow within the vessel. Accordingly, an improved imaging catheter would be desirable.